Photovoltaic or “solar” power systems are becoming increasingly popular with consumers, businesses and utility companies due to decreasing hardware costs, state and federal tax incentives, and increased evidence and awareness of the correlation between CO2 emissions and climate change. A basic solar power system consists of an array of solar panels connected together in one or more strings, a combiner for combining the outputs of the one or more strings, one or more string inverters for converting the combined direct current (DC) output from the strings to alternating current (AC), and a physical interface to AC grid power—typically on the load side of the utility meter, between the meter and the customer's main electric panel. Some energy generation systems may have energy storage devices (e.g., batteries) and are utilized to store DC energy from a PV array or AC grid and to delivery energy to an AC grid or back-up loads. A power control system could be an inverter or one or more PV module based power electronics blocks (e.g., optimizers, micro-inverters and the like).
Since many solar systems are initially paid for by money borrowed from investment banks, a solar system with high reliability (percent uptime) is preferred and easier to get approved by the financier. One factor affecting the reliability of solar power systems is “nuisance shutdowns” or “failures”. Nuisance shutdowns are typically caused by fluctuations in the power grid or other innocuous causes that result in the solar system being immediately and unexpectedly shut down. Other times, shut downs are the result of the failure of one of the components of the solar energy generation system. To maximize the reliability of these systems, the root cause of the shutdown or failure must be identified early and resolved quickly without going through time-consuming site investigations or vendor RMA processes while the array remains non-functional. Further, from the limited evidence available, it is often difficult to determine the root cause of an unexpected shutdown and it may be left unresolved. Consequently, the inability to identify the root cause may result in more fault events further reducing the reliability of the solar power system.